package study.day1;

import java.util.Scanner;

public class Demo2 {
    public static void main(String[] args) {
        //求第几项超过输入的值
        Scanner input = new Scanner(System.in);
        int num = input.nextInt(); //1000
        input.close();
        int i = 1;
        int sum = 1;
        while (sum <= num) {
            i++;
            sum += i;
        }
        System.out.println(i);
    }
}
